Stable isotopes from individual glass eels (Trueman 2019) OPLS-DA scores plots showing clustering of glass eels obtained by (A) positive and (B) negative ionization mode (ZITEK 2019) Glass eel otolith before grinding (ZITEK 2019) Juvenile eel head (ZITEK 2019) Glass eel otolith after grinding (ZITEK 2019) Glass eel otoliths (ZITEK 2019)